Self-Propelled Road-Milling Machine

ABSTRACT

The invention relates to a self-propelled road-milling machine for doing work on surfacings on the ground, and in particular carriageways. The road-milling machine according to the invention is characterised by a signalling arrangement which has at least one control unit for the entry of at least two different states of operation by the driver of the road-milling machine and at least one visual indicator or display unit to indicate or display for the driver of the transporting vehicle the at least two states of operation which are preset with the control unit by the driver of the road-milling machine. The first state of operation may be a request for the transporting vehicle to be braked or stopped and the second state of operation may be a request for the transporting vehicle to be started or to continue travelling. In a preferred embodiment of the visual indicator or display unit, the request for braking or stopping is shown as a cross and the request for starting or continued travel as an arrow.

This application claims priority to German patent application No. 102009 041 842.3 filed Sep. 18, 2009.

The invention relates to a self-propelled road-milling machine for doingwork on surfacings on the ground, and in particular on carriageways.

Self-propelled road-milling machines have long been known. They have amilling arrangement by which material is milled off the surfacing on theground, and a material-handling arrangement by which the material milledoff is fed from the milling arrangement to a discharge point. At thedischarge point, the material is received by a transporting vehicledriving ahead of or following the road-milling machine.

Known road-milling machines are capable of milling off a relativelylarge volume of material in a relatively short time, the conveyor beltof the material-handling arrangement being operated at a relatively highspeed of feed.

When road-milling machines are being used, there is a problem whicharises during travel, namely that of the transporting vehicle receivingthe material discharged by the conveyor belt at the discharge point atthe same time as it is discharged. What needs to be avoided in this caseis, on the one hand, the material being discharged ahead of or to therear of or next to the load-carrying space on the transporting vehicle.What needs to be avoided on the other hand is the transporting vehiclebeing overloaded. The aim is for the material to be evenly distributedalong the entire length of the load-carrying space.

Loading of the milled-off material onto the transporting vehicle isfound to be difficult inasmuch as, although the driver of theroad-milling machine is able to watch the loading process, the driver ofthe transporting vehicle cannot. For as long as road-milling machineshave been known, the usual practice on site has been, for lack of anybetter aids, for the driver of the road-milling machine to use the hornof his machine to direct the driver of the transporting vehicle eventhough the actual purpose of the horn is a different one.

In the case of what is referred to as a front-unloading road-millingmachine, in which the conveyor belt of the material-handling arrangementextends forward in the working direction to a level higher than thefront part of the chassis of the machine, the transporting vehicle, suchas a dumper lorry for example, drives ahead of the road-milling machine.The speed of the transporting vehicle is generally higher than that ofthe road-milling machine in this case. Consequently, the discharge pointmoves from a point at the front towards the rear above the load-carryingspace of the transporting vehicle. The driver of the road-millingmachine is able to watch this happening. When the discharge point is atthe rear end of the load-carrying space, the driver of the road-millingmachine blows his horn to tell the driver of the transporting vehicle tostop his vehicle. Because the road-milling machine continues to travel,the discharge point moves to the front end of the load-carrying space.When the discharge point has reached the front end of the load-carryingspace, the driver of the road-milling machine blows his horn again totell the driver of the transporting vehicle to start moving.

Basically, the requesting of the starting and stopping of thetransporting vehicle by horn signals has proved satisfactory inpractice. For this reason, there has, to date, always been a desire tostick to this standard practice. This practice does have variousdisadvantages but these are not obvious.

In the first place, the horn signals may be a source of irritation toother road users because the drivers of vehicles passing by the site arenot aware or cannot appreciate that the horn signals are instructions tothe driver of the transporting vehicle. Also the horn signals involvenoise, which is a nuisance not only to the personnel on the site butalso to people living close to the site, especially when work is beingdone at night.

On the other hand, the driver of the transporting vehicle may also bedistracted by possible horn signals from passing vehicles, which mayresult in a collision between the transporting vehicle and theroad-milling machine or in the milled-off material being discharged tothe rear of the load-carrying space of the transporting vehicle.

What the constantly repeated horn signals may also result in however isthe site personnel no longer being able to distinguish between a hornsignal by which the driver of the road-milling machine wishes to warnthe site personnel of a danger and a horn signal which is given as aninstruction to the driver of the transporting vehicle. Consequently, forthe site personnel, the horn signal ceases to serve the purpose forwhich it is actually intended.

What is more, it calls for relatively close attention on the part of thedriver of the transporting vehicle for him to detect the horn signals,because they may not be heard on the site. If the driver of thetransporting vehicle misses hearing the horn signal, he does not haveany opportunity of finding out, afterwards, what instructions the driverof the road-milling machine has given.

The object underlying the invention is therefore to provide aself-propelled road-milling machine by which the milled-off material canbe unloaded easily and safely onto the load-carrying space of atransporting vehicle.

The inventors have realised, on site, that the practice which has longbeen customary of giving the driver of the transporting vehicle therequisite instructions with horn signals involves the above-mentioneddisadvantages.

In one embodiment, the road-milling machine according to the inventionis characterised by a signalling arrangement which comprises a controlunit for the entry of at least two different states of operation by thedriver of the road-milling machine and a visual indicator or displayunit to indicate or display for the driver of the transporting vehiclethe at least two states of operation which are preset with the controlunit by the driver of the road-milling machine. The signallingarrangement may also comprise a plurality of control units or visualindicator or display units. It makes sense for there to be a pluralityof control units if for example the road-milling machine has a pluralityof driver's positions. It makes sense for there to be a plurality ofindicator or display units when for example they are arranged to beredundant, e.g. are arranged in pairs, to ensure that there is a clearview of at least one of the indicator or display units under allconditions of operation. The visual indicator or display unit may beprovided on the road-milling machine or as an independent unit on thetransporting vehicle.

What may be meant by the first state of operation is a request for thetransporting vehicle to be braked or stopped and what may be meant bythe second state of operation is a request for the transporting vehicleto be started or to continue travelling. What is crucial is that theindication or display of the two states of operation is visual. Unlikethe horn signals, the visual request for braking or starting cannotirritate other road users or the site personnel. It is also an advantagethat the visual indication or display for the driver of the transportingvehicle is always present. Unlike the horn signals, it is not possiblefor the request for braking or starting to be missed. Even if the driverof the transporting vehicle is not paying attention at the moment whenthe driver of the road-milling machine gives the signal, he can see atany time from the sustained visual signal whether the transportingvehicle is to move or stop. The horn preserves its signalling effectboth for other road users and for the site personnel. The visual signalfrom the indicator or display unit can be perceived even when the driverof the transporting vehicle is distracted by ambient noise. What ismore, the visual indication or display does not involve any noisenuisance for the site personnel or for people living nearby.

The visual indicator or display unit may take different forms. All thatis crucial is that the states of operation are indicated or displayedvisually. In a preferred embodiment, two states of operation areindicated or displayed, with the first state of operation beingindicated or displayed by a first symbol and the second state ofoperation by a second symbol, which symbols are different from oneanother. A variety of symbols may be used. These symbols should nothowever be the same as those used on road signs. The request to brake orstop is preferably shown as a cross and that to start or move as anarrow. The two symbols may also be of different colours. The cross mayfor example be indicated or displayed in red and the arrow in green. Thesymbols may also flash or move across the indicating or display surfaceto make the driver more attentive.

The control unit is preferably arranged at the driver's position on theroad-milling machine at which the driver of the machine is able to watchthe load-carrying space of the transporting vehicle and operate thecontrol unit.

As controls, the control unit may have one or more keys or buttons orswitches with which the two states of operation can be preset.

In an embodiment which is a particular preference, the control unit hasonly one control, by which means mis-operation can be avoided. Thecontrol is preferably a push-button, the control unit being so designedthat, on the push-button being pressed, one state of operation isindicated or displayed until such time as the push-button is pressedagain, following which the other state of operation is then indicated ordisplayed. Consequently, the driver of the machine can change betweenthe two states of operation, which are each permanently indicated ordisplayed by the visual indicator or display unit, simply by pressingthe push-button.

It is however also possible for two push-buttons to be provided on thecontrol unit, with one state of operation being preset with onepush-button and the other state of operation being preset with the otherpush-button. The control unit is then so designed that, on onepush-button being pressed, one state of operation is indicated ordisplayed until such time as the other push-button is pressed, on thepressing of which the other state of operation is indicated ordisplayed.

Particularly if the control takes the form of a push-button, it will befound to be advantageous for the states of operation which are preset tobe shown to the driver of the road-milling machine. This may for examplebe done by means of visual symbols on the control unit or on the rear ofthe indicator or display unit. Indicator lamps or the like may forexample be provided.

Rather than one or two push-buttons as controls, an alternativeembodiment provides a switch having at least two switched positions,with one state of operation being preset with one switched position andthe other state of operation with the other switched position. Theswitch preferably has two switched positions in which it remains, whichmeans that the driver of the machine can at once see from the positionof the switch whether one or the other state of operation has beenpreset without any other further visual signals being required to showthe state of operation.

In the case of a front-unloading road-milling machine, in which theconveyor belt of the material-handling arrangement extends forward inthe working direction to a level higher than the front part of thechassis of the machine, the visual indicator or display unit preferablyhas an indicating or display surface which faces in the direction ofoperation of the milling machine. Consequently, the driver of thetransporting vehicle which is being driven ahead of the front-unloadingroad-milling machine is able to see the indicating or display surface ofthe visual indicator or display unit in his rear-view mirror.

The visual indicator or display unit having the indicating or displaysurface is advantageously arranged on the road-milling machine in such away that the driver of the transporting vehicle can see the indicatingor display surface in the left-hand and/or right-hand rear-view mirrorof the transporting vehicle. The visual indicator or display unit ispreferably arranged on one or both longitudinal sides of the chassis ofthe machine. The indicator or display unit should be arranged at thesame height as that at which the rear-view mirror of the transportingvehicle is situated.

Known road-milling machines have a rear-view mirror on one or bothlongitudinal sides. An embodiment which is a particular preference makesprovision for the visual indicator or display unit to be arranged on thefront of the rear-view mirror of the road-milling machine. Thisembodiment has the advantage that the indicator or display unit is apart of the rear-view mirror, which latter is arranged in the field ofvision of the driver of the transporting vehicle. What is more, theincorporation of the indicator or display unit in the rear-view mirrordoes not call for any additional items which might obstruct the visionof the driver of the road-milling machine to be mounted on the latter.

In an alternative embodiment, the visual indicator or display unit takesthe form of an independent unit which is not arranged on theroad-milling machine but is arranged in or on the transporting vehicle.In this embodiment, the control unit has a transmitting unit fortransmitting a signal for the at least two states of operation and theindicator or display unit has a receiving unit for receiving the signalfor the at least two states of operation. The transmitting and receivingunits may be radio transmitters and receivers which are familiar to theperson skilled in the art. The alternative embodiment has the advantagethat the visual indicator or display unit can be arranged in thedriver's cab directly in the field of vision of the driver of thetransporting vehicle. There is thus no need for the driver of thetransporting vehicle to watch the indicator or display unit in hisrear-view mirror. It is for example possible for the visual indicator ordisplay unit to take the form of a portable unit which is handed to thedriver of the transporting vehicle on the site. It is however alsopossible for the visual indicator or display unit to be permanentlyinstalled in the transporting vehicle. It is for example possible forthe visual indicator or display unit to take the form of what isreferred to as a head-up display, which is familiar to the personskilled in the art.

In another preferred embodiment, the signalling effect of the visualindicator or display unit is further boosted by an audio signal for thedriver of the transporting vehicle being given in addition when theindication or display changes from one state of operation to the other.This is particularly advantageous in the embodiment where the visualindicator or display unit is an independent unit which can be arrangedin the driver's cab of the transporting vehicle. The volume of the audiosignal does not need to be loud in this case, and it is thus not anuisance to others.

A plurality of embodiments of the invention will be explained in detailbelow by reference to the accompanying drawings. In the drawings:

FIG. 1 is a simplified representation of a road-milling machine togetherwith a transporting vehicle,

FIG. 2A is a view from the front of the visual indicator or displayunit, the symbol shown being that for stopping,

FIG. 2B shows the visual indicator or display unit, the symbol shownbeing that for starting,

FIG. 2C is a view of the visual indicator or display unit from the rear,

FIG. 2D is a view of the visual indicator or display unit from the side,

FIG. 3 shows a first embodiment of control unit,

FIG. 4 shows a second embodiment of control unit,

FIG. 5 shows a further embodiment of control unit,

FIG. 6 shows a further embodiment of indicator or display unit.

FIG. 1 is a simplified schematic representation of a road-millingmachine which is a front-unloading road-milling machine. Theroad-milling machine 1 has a chassis 2 and running gear 3. The driver'sposition 4 is situated between the front and rear parts of the chassis 2of the machine. As well as this, the road-milling machine also has amilling arrangement 5, which may also be referred to as a milling drum,arranged on the chassis 2 of the machine, by which material can bemilled off the surface of a road.

A material-handling arrangement 6, which may also be referred to as amaterial-handling conveyor, loads the milled-off material onto atransporting vehicle 10, such as a dumper lorry for example, whichdrives ahead of the road-milling machine. The material-handlingarrangement 6 has a conveyor belt 7 which extends forward in the workingdirection A to a level higher than the front part of the chassis 2 ofthe machine. The material is fed at a relatively high speed and it isdischarged, in the direction of working A, above the load-carrying space9 of the transporting vehicle 10 at the discharge point 8 ahead of thefront end of the conveyor belt 7. Discharge point 8 may also be referredto as a discharge area.

The transporting vehicle 10 is loaded as follows. The transportingvehicle 10 travels at a somewhat higher speed than the road-millingmachine 1, and the discharge point 8 thus moves from the front end tothe rear end of the load-carrying space 9. The transporting vehicle 10then stops whereas the road-milling machine 1 continues its travel.Consequently, the discharge point 8 moves back to the front end of theload-carrying space 9. This process is repeated until such time as thetransporting vehicle is fully loaded.

The road-milling machine 1 has an arrangement which signals to thedriver of the transporting vehicle 10 when he is to start or stop thetransporting vehicle. This arrangement will be described in detailbelow.

The signalling arrangement comprises a visual indicator or display unit11 and a control unit 12. In the first embodiment, the visual indicatoror display unit 11 and the rear-view mirror of the road-milling machineare arranged in a common housing, and thus form a unit which, in thepresent embodiment, is arranged to project outwards on that side of thechassis 2 of the machine which is on the left in the direction ofworking A. The visual indicator or display unit 11 is merely indicatedin FIG. 1. FIGS. 2A to 2D are views of the visual indicator or displayunit 11 from the front, rear and side.

The visual indicator or display unit 11 has a housing 13 having anindicating or display surface 14 which faces forward in the direction ofworking A, the said indicating or display surface 14 thus being situatedin the field of vision which the rear-view mirror 10A of the driver ofthe transporting vehicle 10 has.

In the present embodiment, two symbols which are preset by the driver ofthe road-milling machine 1 from the control unit 12 are indicated ordisplayed alternately on the visual indicator or display unit 11. Thefirst symbol, which tells the driver to brake or stop, is a cross 15(FIG. 2A), whereas the second symbol, which tells the driver to start orto continue moving, is an arrow 16 (FIG. 2B). The cross 15 and arrow 16are preferably of different colours and in particular the cross is redand the arrow green. The red cross and the green arrow are preferablycomposed of a plurality of illuminable segments 15A, 16A which arebacklit by red and green LED's (not shown) respectively. The individualilluminable segments are driven in such a way that either a red cross 15or a green arrow 16 is shown.

FIG. 2C shows the rear of the housing 13 of the visual indicator ordisplay unit 11, on which latter the adjustable rear-view mirror 17 ofthe road-milling machine 1 is situated. The housing 13 of the visualindicator or display unit 11 is fastened to a bracket 18 on the chassis2 of the machine (FIG. 2D).

FIG. 3 shows the control unit 12, which is arranged, at the driver'sposition 4, on the control panel for the driver of the road-millingmachine 1. The control unit 12 has a push-button 20 and two indicatorlamps 21, 22, these being in particular a red and a green LED, and anelectrical circuit (not shown). The control unit 12 and the visualindicator or display unit 11 communicate by way of an electrical line23. The electrical circuit is so designed that, on the push-button 20being pressed, the red cross 15 (FIG. 2A) is indicated or displayed onthe indicating or display surface 14 of the visual indicator or displayunit 11 until such time as the push-button 20 is pressed again, afterwhich the green arrow 16 (FIG. 2B) is then indicated or displayed. Onthe push-button 20 being pressed again, the red cross (FIG. 2A) is thenindicated or displayed again. The driver of the road-milling machine 1is thus able to give the driver of the transporting vehicle 10 thenecessary instructions simply by pressing the push-button 20. The driverof the machine is told what the state of operation at the time isbecause the red LED 21 is lit when the red cross is being indicated ordisplayed and the green LED 22 is lit when the green arrow is beingindicated or displayed.

FIG. 4 shows an alternative embodiment of control unit 12 which differsfrom the control unit which was described by reference to FIG. 3 in thata switch 24 which has two switched positions in which it remains isprovided rather than the push-button 20. The first switched position ofthe switch 24 is shown in solid lines in FIG. 4 and the second switchedposition in dashed lines. When the switch 24 is in the first switchedposition the red cross (FIG. 2A) is indicated or displayed, whereas thegreen arrow (FIG. 2B) is indicated or displayed when the switch is inthe second switched position. The driver of the machine can thus seesimply from the position of the switch what instructions he is giving tothe driver of the transporting vehicle. Indicator lamps can be dispensedwith in this case.

In the embodiments which are described above, the visual indicator ordisplay unit 11 is part of the road-milling machine 1. However, in analternative embodiment the visual indicator or display unit forms anindependent unit which is arranged in or on the transporting vehicle 10.The visual indicator or display unit may for example be handed over tothe driver of the transporting vehicle and may be arranged by the latterin the cab of the vehicle. The indicator or display unit may howeveralso be permanently installed in the cab of the vehicle, such as in theform of what is referred to as a head-up display. In this embodiment,communication between the control unit 12 and the visual indicator ordisplay unit 11 is not by way of an electrical line but by a radio link.The control unit 12 therefore has a transmitting unit 25, which ismerely indicated, and the visual indicator or display unit 11 has areceiving unit 26, which is also merely indicated. The transmitting unit25 transmits a radio signal which specifies one or other state ofoperation and which the receiving unit 26 receives, one or other stateof operation thus being indicated or displayed on the indicating ordisplay surface 14. Otherwise this embodiment corresponds to theembodiments described above, the items which correspond to one anotheralso being given the same reference numerals. As well as the indicatingor display surface 14, the indicator or display unit 11 also has anaudio signal emitter 27 which is situated in the housing 13 of theindicator or display unit. At any change in what is indicated ordisplayed visually from one state of operation to the other, i.e.stopping and travelling, the audio signal emitter 27 emits an audiosignal which the driver of the transporting vehicle is able to perceiveclearly in the cab of his vehicle but which is not a nuisance to thesite personnel or to other road users.

What is claimed is:
 1. A self-propelled road-milling machine,comprising: a chassis; a driver's position arranged on the chassis for adriver of the road-milling machine; a milling drum supported from thechassis for milling off material; a material handling conveyor supportedfrom the chassis for feeding the milled off material to a dischargepoint where the milled off material is to be received by a transportingvehicle separate from the road-milling machine; at least one controlunit carried by the road-milling machine, the control unit beingconfigured to receive during forward operation of the road-millingmachine an entry by the driver of the road-milling machine of an inputcorresponding to one of at least two different states of operation, theat least two states of operation including: a first state of operationwherein the transporting vehicle is to move forward; and a second stateof operation wherein the transporting vehicle is to stop; and at leastone visual indicator operably associated with the control unit andconfigured to indicate to a driver of the transporting vehicle which oneof the at least two states of operation has been entered on the controlunit by the driver of the road-milling machine.
 2. The road-millingmachine of claim 1, wherein: the visual indicator is configured toindicate a first symbol for the first state of operation and a secondsymbol for the second state of operation, the first symbol beingdifferent from the second symbol.
 3. The road-milling machine of claim1, wherein: the at least one control unit is arranged at the driver'sposition.
 4. The road-milling machine of claim 1, wherein: the at leastone control unit includes a control member for presetting the first andsecond states of operation.
 5. The road-milling machine of claim 4,wherein: the control member comprises a push-button, the control unitbeing operable so that, on the push-button being pressed one of thestates of operation is indicated on the visual indicator until such timeas the push-button is pressed again, following which another of thestates of operation is indicated on the visual indicator.
 6. Theroad-milling machine of claim 4, wherein: the control member comprises aswitch having at least two switched positions, the switch remaining in aselected one of the switched positions until the driver of theroad-milling machine moves the switch to another one of the switchedpositions.
 7. The road-milling machine of claim 1, wherein: thematerial-handling conveyor extends forward in a working direction ofoperation to a level higher than a front part of the chassis of theroad-milling machine; and the visual indicator includes an indicatingsurface facing in the working direction of operation.
 8. Theroad-milling machine of claim 1, wherein: the chassis has twolongitudinal sides; and the visual indicator is arranged on at least oneof the two longitudinal sides of the road-milling machine.
 9. Theroad-milling machine of claim 8, further comprising: at least onerear-view mirror for the driver of the road-milling machine, the atleast one rear-view mirror arranged on at least one of the twolongitudinal sides of the road-milling machine; and wherein the at leastone rear-view mirror and the at least one visual indicator form at leastone unit.
 10. The road-milling machine of claim 1, wherein: the at leastone control unit includes a transmitter configured to transmit a signalcorresponding to the state of operation entered on the control unit bythe driver of the road-milling machine; and the at least one visualindicator comprises an independent indicator unit separate from theroad-milling machine, the indicator unit being located in or on thetransporting vehicle and configured to receive the signal from thetransmitter.
 11. The road-milling machine of claim 10, wherein: theindependent indicator unit includes an audio signal emitter configuredto emit an audio signal when the visual indicator changes from one stateof operation to another state of operation.
 12. The road-milling machineof claim 1, wherein: the visual indicator is configured to indicate afirst symbol for the first state of operation and a second symbol forthe second state of operation, the first symbol and the second symbolbeing shown in different colours.
 13. The road-milling machine of claim1, wherein: the control unit includes a visual control unit indicatorconfigured to indicate which one of the two different states ofoperation has been entered by the driver of the road-milling machine,the visual control unit indicator being visible from the driver'sposition.
 14. The road-milling machine of claim 1, wherein: the at leastone visual indicator is located on the road-milling machine and facesforward so that the at least one visual indicator may be viewed by thedriver of the transporting vehicle in a rear-view mirror of thetransporting vehicle.
 15. The road-milling machine of claim 14, wherein:the road-milling machine includes a rear-view mirror having aforward-facing surface and the at least one visual indicator is locatedupon the forward-facing surface of the rear-view mirror of theroad-milling machine.